address review comments

tests/run-make/rustdoc-merge-no-input-finalize/rmake.rs

@@ -16,6 +16,7 @@ fn main() {
         .arg(format!("--parts-out-dir={}", parts_out_dir.display()))
         .arg("--merge=none")
         .run();
+    assert!(parts_out_dir.join("crate-info").exists());
 
     let output = rustdoc()
         .arg("-Zunstable-options")
@@ -23,6 +24,5 @@ fn main() {
         .arg(format!("--include-parts-dir={}", parts_out_dir.display()))
         .arg("--merge=finalize")
         .run();
-
-    output.assert_exit_code(0);
+    output.assert_stderr_not_contains("error: the compiler unexpectedly panicked. this is a bug.");
 }